THE MOLECULAR BASIS OF INHERITANCE
DNA MAKES RNA MAKES PROTEIN
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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5’
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3’
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both ends
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it’s not put on the pre-mRNA
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Detailed explanation-1: -The 5’ cap is added to the first nucleotide in the transcript during transcription. The cap is a modified guanine (G) nucleotide, and it protects the transcript from being broken down. It also helps the ribosome attach to the mRNA and start reading it to make a protein.
Detailed explanation-2: -All eukaryotic mRNAs are capped at their 5′ end, shortly after transcription initiation. The cap consists of a guanine nucleotide methylated at the N7 position, and is linked to the 5′ nucleotide of the RNA through an unusual 5′-5′ pyrophosphate linkage (m7GpppN) (Shatkin, 1976; Furuichi and Shatkin, 2000).
Detailed explanation-3: -mRNA capping in eukaryotes Capping is the first modification made to RNA polymerase II-transcribed RNA and takes place co-transcriptionally in the nucleus as soon as the first 25–30 nts are incorporated into the nascent transcript (6, 7).
Detailed explanation-4: -The cap is added by the enzyme guanyl transferase. This enzyme catalyzes the reaction between the 5’ end of the RNA transcript and a guanine triphosphate (GTP) molecule.
Detailed explanation-5: -The cap structure found at the 5′ end of eukaryotic mRNAs consists of a 7-methylguanosine (m7G) moiety linked to the first nucleotide of the transcript via a 5′–5′ triphosphate bridge1 (Fig. 1a).